I don't agree with you.
The website file has 1284 entries (21985 words) in total. It contains all the words used in the Calibre site.
But only 21% are really useful when navigating the site.
So instead of asking for 21,985 total words to be translated , if someone translate just the proper 4,500 words the site interface will be fully navigated in a new language (except the "Old" new features page and the changelog page)
Explanation: The site has 3 main entries types considering its use (approximate calculations):
A - 272 entries (4545 words) - Should be translated!
Actual "useful" site interface entries.
B - 231 entries (6013 words) - no point to translate this!
Entries are for "New" functionalities (but actually they are from Calibre old versions... since 0.7 version).
This is just for history and could be in an archive non translated page!
Entries can be seen in pages like this:
https://calibre-ebook.com/new-in/seven
https://calibre-ebook.com/new-in/twelve
https://calibre-ebook.com/new-in/eleven
https://calibre-ebook.com/new-in/ten
C - 781 entries (11427 words) - no point to translate this.
Entries describes the bugs and features since release 3.0 visible in this page:
https://calibre-ebook.com/whats-new
This is just for tech users not for main users. And its the main task here!
If someone is considering to start now to translate the website interface will not be amused to have to translate a description of a bug fixed in 16 Jun 2017!